1. Technical Field
This description pertains generally to sensors, and more particularly to a plasmon laser sensor.
2. Background Discussion
One particularly beneficial application of plasmonics thus far has been in the field of sensing, where the interaction of a nanoscale localized field with analytes leads to high sensitive detection in real-time and label-free fashion. However, previous designs have been based on passively excited surface plasmons (SPs), in which sensitivity is intrinsically limited by low quality factors induced by metal losses.
While cavities in which the light-matter interaction is greatly enhanced provide a promising platform for sensing, the sensitivity of these detectors is ultimately determined by the quality factor of the cavity modes and the surface to volume ratio, and the diffraction limit of light creates a hurdle to improve these two features simultaneously in a conventional optical cavity. Surface plasmons (SP) are able to achieve nanoscale confinement of electromagnetic fields, but existing SP sensors are passively excited and suffer from the intrinsically high ohmic losses in metals, resulting in low quality factor of the resonances and thus limiting its sensitivity.
Accordingly, an object of the present description is an SP sensor with active (gain enhanced) excitations that exhibit well-confined strong local fields, increased radiating power, and dramatically narrowed line-width for achieving higher sensitivities due to the amplification of the SPs.